Technical Field
The present invention relates to a spectrometer and a method of spectroscopy, and more particularly to Fourier transform spectroscopy.
Background Art
In one method of Fourier transform spectroscopy, a light ray from a light source is split into two light rays using a beam splitter, and then these two light rays are made to interfere with one another.
Patent Document 1 discloses an example of a spectrometer used for Fourier transform spectroscopy. In Patent Document 1, a Wollaston prism is used as the beam splitter. A Wollaston prism splits a light ray from a light source into an ordinary light ray and an extraordinary light ray. The ordinary light ray and the extraordinary light ray then interfere with one another on a detector.
Patent Document 2 also discloses an example of a spectrometer used for Fourier transform spectroscopy. In Patent Document 2, a Savart plate is used as the beam splitter. A Savart plate also splits a light ray from a light source into an ordinary light ray and an extraordinary light ray. The ordinary light ray and the extraordinary light ray are then focused onto a detector using a single lens. In this way, the ordinary light ray and the extraordinary light ray interfere with one another.
Furthermore, in Patent Document 2, a polarizer is arranged between the Savart plate and the lens. The detector detects an interference fringe (a first interference fringe) created by the light beams that pass through the polarizer. In Patent Document 2, after this interference fringe is detected, the orientation of the transmission axis of the polarizer is changed. The detector then detects the new interference fringe (a second interference fringe) created by the light beams that pass through the polarizer. In Patent Document 2, the difference between the first interference fringe and the second interference fringe is then calculated. Patent Document 2 discloses that calculating this difference removes background noise.